The piece that is most valuable from the Mimecast standpoint will be the sandboxing feature.
Mimecast Email Security is known for its sandboxing and user-friendly console, seamlessly integrating with Microsoft 365 to reduce phishing emails. It offers commendable impersonation protection; however, pricing is high. Concerns about detection rates, false positives, blocklisted servers, and support system exist. Mimecast's technical superiority contrasts with a need for threat response improvement and user concerns over service reliability, particularly regarding company reputation due to unpredictable email delivery issues.